RESUMEN
The susceptibilities to macrolides and telithromycin of 161 Streptococcus pyogenes and 145 Streptococcus pyogenes strains, consecutively isolated from five Greek hospitals, were determined by Etest. Moreover, mechanisms of resistance to macrolides were phenotypically and genetically determined by double disk induction test and PCR, respectively. Of the S. pneumoniae and S. pyogenes isolates, 42.8% and 30.8%, respectively, were found to be resistant to erythromycin. Of the erythromycin-resistant S. pneumoniae and S. pyogenes isolates, 57.5% and 59.5%, respectively, displayed the M phenotype and harbored the mefA/E gene. Telithromycin was found to be more active than both erythromycin and clarithromycin against both species, with considerably lower MIC50 and MIC90 values.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Cetólidos , Macrólidos , Streptococcus pneumoniae/efectos de los fármacos , Streptococcus pyogenes/efectos de los fármacos , Claritromicina/farmacología , Relación Dosis-Respuesta a Droga , Eritromicina/farmacología , GreciaRESUMEN
Seventeen Klebsiella pneumoniae clinical isolates carrying the bla(VIM-1) metallo-beta-lactamase gene were collected in the intensive care units of three hospitals in Athens, Greece, in 2002. They exhibited various carbapenem resistance levels (Etest MICs of imipenem ranged from 4 to 32 microg/ml). All isolates gave positive results by the imipenem-EDTA synergy Etest. The isolates were classified into four main types by pulsed-field gel electrophoresis; the majority of the isolates (5 and 10 isolates) belonged to two types. The bla(VIM-1) gene cassette was part of the variable region of a class 1 integron that also included aac6, dhfrI, and aadA. This structure was carried by transferable plasmids.
Asunto(s)
Infección Hospitalaria/microbiología , Infecciones por Klebsiella/diagnóstico , Klebsiella pneumoniae/enzimología , beta-Lactamasas/genética , Secuencia de Bases , Cartilla de ADN , Electroforesis en Gel de Campo Pulsado , Grecia , Hospitales , Humanos , Unidades de Cuidados Intensivos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Mapeo RestrictivoRESUMEN
The presence of conjugative R plasmids as well as the possible similarities among them were studied in nine ampicillin-resistant Salmonella enteritidis isolates and nine ampicillin-resistant Escherichia coli isolates from the normal fecal flora that were simultaneously isolated from nine epidemiologically unrelated outpatients. It was found that in eight patients, ampicillin resistance in S. enteritidis was encoded by ca. 34-MDa transferable plasmids very similar to those found in a recent study of the epidemiology of ampicillin-resistant S. enteritidis in Greece (A.C. Vatopoulos, E. Mainas, E. Balis, E.J. Threlfall, M. Kanelopoulou, V. Kalapothaki, H. Malamou-Lada, and N.J. Legakis, J. Clin. Microbiol. 32:1322-1325, 1994). Moreover, transferable R plasmids with the same molecular size and restriction pattern were found in the normal flora E. coli of two of these patients. This finding, if confirmed by further studies, is consistent with the hypothesis that normal flora E. coli could act as a reservoir of resistant genes and, consequently, as a factor in the dissemination of these genes among pathogens of human and animal origin such as Salmonella spp. and needs to be examined further.
Asunto(s)
Sistema Digestivo/microbiología , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Factores R/genética , Salmonella enteritidis/genética , Salmonella enteritidis/aislamiento & purificación , Resistencia a la Ampicilina/genética , Animales , Conjugación Genética , Escherichia coli/efectos de los fármacos , Heces/microbiología , Humanos , Fenotipo , Salmonella enteritidis/efectos de los fármacos , Virulencia/genéticaRESUMEN
During the last 6 years in Greece, there has been a significant increase in the number of ampicillin-resistant Salmonella clinical isolates reported. In this study 23 ampicillin-resistant Salmonella strains, consecutively isolated from patients with epidemiologically unrelated cases of food poisoning, were investigated. By serotyping and phage typing, 21 of these strains were identified as Salmonella enteritidis phage type 6a, 1 was identified as Salmonella typhimurium, and 1 was identified as Salmonella saintpaul. By plasmid pattern analysis, the 21 S. enteritidis strains were further differentiated into five groups. Group I consisted of 5 strains (carrying two plasmids of ca. 38 and 34 MDa), group II consisted of 10 strains (three plasmids of ca. 38, 34, and 2.5 MDa), group III consisted of 3 strains (four plasmids of ca. 38, 34, 15, and 2.5 MDa), group IV consisted of 1 strain (five plasmids of ca. 100, 38, 34, 24, and 15 MDa), and group V consisted of 2 strains (three plasmids of ca. 100, 38, and 24 MDa). Ampicillin resistance was easily transferred to Escherichia coli and was associated with the transfer of the 34-MDa plasmid, classified in the N incompatibility group for all strains of groups I to IV, and with the transfer of the 100-MDa plasmid for the group V strains. EcoRI restriction endonuclease digestions showed an extensive homology among the 34-MDa conjugative R plasmids. Hybridizations of the EcoRI restriction fragments of the 34-MDa plasmids with a TEM-type probe revealed the locus of the beta-lactamase gene to be situated on a ca. 6.6-MDa fragment, common in all plasmids. These results indicate that ampicillin resistance in Greece is due to the spread of a limited number of clones of S. enteritidis phage type 6A, carrying related 34-MDa R plasmids. Work is in progress to obtain a better understanding of ampicillin resistance in S. enteritidis.